Test: Proteins (May 26) - NEET MCQ

A fibrous protein is a thread like which may occur singly or in groups. They are tough, non-enzymatic and structural proteins. It is insoluble in water e.g., Keratin. Some fibrous protein is contractile protein found in myosin of muscles and connective tissue (tendons, bones, and cartilage) are collagen. Thus, the correct option is A.

Proteins are building blocks of the body. The proteins are made up of amino acids. The amino acids are linked together by peptide bonds to form a protein. The amino acids consist of amine group made up of nitrogen and hydrogen and the carboxyl group at the end and a side chain of R group which is specific to a particular amino acid. This specific group brings a variability to the proteins. If R group is H it is glycine while if it is CH₂ it is alanine. The sequence of amino acids determines the protein. 

• Amino Acids: Amino acids are the building blocks of proteins. They contain an amino group, a carboxyl group, and a side chain.


• Peptide Bonds: Amino acids chemically bond together through peptide bonds. A peptide bond forms between the amino group of one amino acid and the carboxyl group of another amino acid.


• Polypeptide Chain: As amino acids bond together through peptide bonds, a chain of amino acids called a polypeptide chain is formed.


• Folding and Structure: The polypeptide chain then folds into a specific three-dimensional structure to form a functional protein.


• Enzymes: Enzymes are specialized proteins that catalyze biochemical reactions in living organisms. They have specific active sites where substrates bind and reactions occur.


• Functionality: The specific sequence of amino acids in an enzyme determines its structure and functionality. Enzymes play crucial roles in various biological processes.

Hormones are chemical substances which are released in the body for regulation and metabolism in cells.

Many hormones such as insulin and parathormone are proteinic in nature.

Glycoproteins are proteins which contain oligosaccharide chains (glycans) covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycosylation. Secreted extracellular proteins are often glycosylated.

A conjugated protein is a protein that functions in interaction with other (non-polypeptide) chemical groups attached by covalent bonding or weak interactions. Many proteins contain only amino acids and no other chemical groups, and they are called simple proteins.

Amino acids joined by peptide bonds form proteins. Twenty types of amino acids are present in natural proteins.

Proteins are building blocks of the body. The proteins are made up of amino acids. The amino acids are linked together by peptide bonds to form a protein.The amino acids consists of amine group made up of nitrogen and hydrogen and the carboxyl group at the end and a side chain of R group which is specific to a particular amino acid. The amine group (NH₂) is made up of nitrogen and hydrogen.

So, the correct answer is option D.

Human insulin is a peptide hormone composed of 51 ammo acids and has a molecular weight of 5805 Da.(∼6 Kda). In this molecule, there are two polypeptide chains (A and B) held together by disulphide bridge.

Most enzymes are proteins and therefore their function is specific to their structure. Enzymes function as a catalyst to increase the rate of virtually all the chemical reactions that take place in a living system. It is the same with enzymes and substrates.